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Fiber Path Optimization in a Variable-Stifness Cylinder to Maximize Its Buckling Load Under External Hydrostatic Pressure
摘要： The optimum paths and orientations for curvilinear and straight fibers in composite cylindrical shells of variable and constant stiffness under external hydrostatic pressure are obtained and compared. The optimization was performed for several length-to-diameter ratios of the shells. Results showed that the buckling pressure of the variable-stiffness shell was by about 30% higher than that of the constant-stiffness one. This increase in the buckling pressure was obtained by locating fibers in the hoop direction in the middle of the cylinder and orienting the fibers toward the longitudinal direction on cylinder edges.
关键词： variable stiffness,cylindrical shell,external hydrostatic pressure,buckling,curvilinear fiber
更新于2025-09-23 15:23:52
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Donor Impurity States in Semiconductor Zincblende Nitride Quantum Systems as a Source of Nonlinear Optical Response
摘要： The optical absorption and the optical rectification coefficients associated to hydrogenic impurity interstate transitions in zincblende GaN-based nanostructures of the quantum wire type are investigated. The system is assumed to have cylindrical shape and the influence of external tuning probes such as hydrostatic pressure and static electric fields is particularly taken into account. The electron states are obtained within the effective mass approximation, via the exact diagonalization of the donor-impurity Hamiltonian with parabolic confinement. The nonlinear optical coefficients are calculated using a nonperturbative solution of the density-matrix Bloch equation. Our results show that the resonance-related features of the optical response become shifted in the frequency range of the incident radiation due to the effect of the hydrostatic pressure, the strength of the applied field and the change in the impurity center position.
关键词： Quantum Wire,Nonlinear Optics,Hydrostatic Pressure,Zincblende GaN
更新于2025-09-23 15:22:29
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Dependence on hydrostatic pressure in two-dimensional triangular photonic crystals
摘要： The plane wave expansion method is used to calculate photonic band structures for transverse electric (TE) polarization, in a two-dimensional (2D) photonic crystal with a hexagonal lattice composed air holes with triangular cross sections embedded in a semiconductor (GaAs) background. This study focuses on the dependence of the GaAs dielectric constant on pressure and temperature. The air holes are isosceles triangles with fixed areas. We found that the width of the photonic band gap increases, when the internal angle of the triangle and the angle of rotation in the unit cell are increased at constant hydrostatic pressure values. The width of the photonic band gap remains unchanged when the hydrostatic pressure is increased at fixed internal and rotation angle values. In addition, when considering an H1 defect in the crystal, using the supercell technique, we find that the number of defective modes within the photonic band gap increases with the triangle rotation in the unit cell.
关键词： plane wave expansion method,hydrostatic pressure,defect mode,Photonic crystal,semiconductor
更新于2025-09-23 15:22:29
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Aggregation-Induced Emission-Based Polymer Materials: Ratiometric Fluorescence Responses Controlled by Hydrostatic Pressure
摘要： Dual fluorescence materials that exhibit controllable ratiometric changes in response to various external stimuli have attracted much attention from the viewpoints of applied material science and sensing/imaging technologies in interfaces. In the present study, we found fluorescence polymers based on aggregation-induced emission (AIE) characters. The functional AIE polymers can be converted to ratiometric fluorophores upon electronic excitation, and subsequently, their optical/photophysical properties can also be regulated by hydrostatic pressure or isotropic mechanical force. The degree of substitution (DS) of AIE branches on the polymer backbone plays critical roles in influencing the pressure-induced ratiometric fluorescence responses. The present study provides significant guidelines for developing AIE-based smart applied materials to response in hydrostatic pressure.
关键词： fluorescence spectroscopy,excited-state behavior,polyethylene,hydrostatic pressure,aggregation-induced emission,luminescence materials
更新于2025-09-23 15:21:01
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Temperature and hydrostatic pressure effects on the electronic structure, optical properties of spherical segment quantum dot/wetting layer and group velocity of light
摘要： To investigate hydrostatic pressure and temperature effects on electron energy levels of an InAs spherical segment quantum dot with wetting layer embedded in GaAs barrier, we use the finite element method to solve the Schr?dinger equation in the effective mass approximation. Results show that the ground, the first and the second excited state energies decrease (increase) as the hydrostatic pressure (temperature) increases for the constant temperature (pressure). Moreover, given the optical properties of the system interacting with two laser fields, red (blue) shifts are observed in the linear and nonlinear absorptions and dispersions for the probe pulse as the hydrostatic pressure (temperature) increases. Furthermore, as the hydrostatic pressure increases, the maximum of the group velocity of light inside the slow light frequency range increases and the slow light frequency range shifts to the lower probe frequencies.
关键词： temperature,group velocity of light,hydrostatic pressure,optical property,quantum dot/wetting layer
更新于2025-09-23 15:21:01
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THz cutoff frequency and multifunction Ti 2Ba2Ca2Cu3O10/GaAs photonic bandgap materials
摘要： By using the transfer matrix method (TMM), we theoretically explore the transmittance properties and cuto? frequency of one-dimensional photonic crystal (1DPCs) within the terahertz frequency region. The present structure consists of high-temperature superconductor and semiconductor layers. The results of the calculations represent the e?ects of various parameters on the cuto? frequency. We have used the two-?uid model as well as the Drude model to describe the permittivity of superconductor and semiconductor. Further, we consider that the permittivity of both the materials is depending on the hydrostatic pressure. The present results show that with the increasing of di?erent parameters as the operating temperature, the thickness of semiconductor, and the ?lling factor of semiconductor, then the cuto? frequency shift to lower frequencies regions. By the increasing of superconductor thickness, hydrostatic pressure, doping concentration and ?lling factor of the superconductor, we found the cuto? frequency shifts to higher frequency regions. These results indicate that cuto? frequency can be modi?ed through these di?erent parameters. Finally, the present design could be useful for many optical systems as the optical ?lter, re?ector and photoelectronic applications in the Terahertz regime.
关键词： Cuto? frequency,transfer matrix method,photonic crystal,doping concentration,hydrostatic pressure,two-?uid model,Drude model
更新于2025-09-23 15:21:01
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Excitonic properties in an asymmetric quantum dot nanostructure under combined influence of temperature and lateral hydrostatic pressure
摘要： Simultaneous influences of temperature and lateral hydrostatic pressure combined to axial asymmetric confinement potential and size effects on the behavior of the exciton in 0D (cid:1833)(cid:1853)(cid:1827)(cid:1871)/(cid:1833)(cid:1853)((cid:2869)(cid:2879)(cid:3051)(cid:3285))Al((cid:2934)(cid:3168)) asymmetric cylindrical quantum dot (QD) nanostructure are investigated. Our calculations are performed in the framework of the effective mass approximation by using a variational method with a robust trial wave function through taking into account the dependence of exciton properties on the QD sizes, the axial asymmetric confinement potential, the temperature and the pressure. Variation of the excitonic binding energy, photoluminescence energy transition and band gap energy are discussed according to temperature and hydrostatic pressure for different confinement regimes and various potential wells. Our numerical findings show that the applied pressure favors the attraction between electron and hole while the temperature tends to decrease the exciton binding energy. Furthermore, the photoluminescence energy is decreasing function of the temperature and increasing function of the pressure. The opposing influences caused by temperature and lateral hydrostatic pressure with contribution of variation of axial asymmetric confinement potential reveal a significant practical interest and offer an alternative manner to the tuning of the excitonic transition in optoelectronic devices.
关键词： Exciton,Temperature,Asymmetric potential,Quantum dots,Hydrostatic pressure
更新于2025-09-19 17:13:59
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Achievement of Higha??Performance Nondoped Blue OLEDs Based on AIEgens via Construction of Effective Higha??Lying Chargea??Transfer State
摘要： There remains an urgent demand for high-quality blue luminogens that can simultaneously achieve high photoluminescence quantum yield (PLQY) in film and high exciton utilization efficiency (EUE) in the electroluminescence (EL) process. In this study, a referable molecular design strategy is developed for blue luminogens via constructing low-lying locally excited (LE) state with an aggregation-induced emission (AIE) characteristic and high-lying charge-transfer (CT) state for the effective triplet-to-singlet conversion channel. 2TriPE-BPI-MCN with the insertion of p-cyano and o-methyl groups is designed to compare with its matrix framework (2TriPE-BPI). They have analogous properties of the lowest singlet (S1) states with blue emission and free of concentration quenching in film; however, 2TriPE-BPI-MCN exhibits unusual response for hydrostatic pressure owing to its S2 state CT characteristics. Therefore, 2TriPE-BPI-MCN can harness more electrogenerated excitons than 2TriPE-BPI, resulting in a better EL performance in nondoped blue organic light-emitting diodes (OLEDs) (CIEx,y = 0.153, 0.147) with high external quantum efficiency of 4.6% and negligible efficiency roll-off. These findings could open a feasible avenue to develop high-quality blue luminogens for high-performance nondoped blue OLEDs.
关键词： organic light-emitting diodes,blue emission,hydrostatic pressure,aggregation-induced emission,charge-transfer state
更新于2025-09-19 17:13:59
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Binding energies and photoionization cross-sections of donor impurities in GaN/AlxGa1a??xN spherical quantum dot under hydrostatic pressure
摘要： In this paper, the binding energy and photoionization cross-section of donor impurity state in GaN/AlxGa1?xN quantum dot structure are studied theoretically by using variational method. The variation of binding energy and photoionization cross-section with core and shell sizes at di?erent impurity locations under hydrostatic pressure is calculated numerically. The results show that the binding energy decreases monotonously with the core size at di?erent impurity locations for GaN/AlxGa1?xN core/shell quantum dot. In contrast, for the inverted core/shell quantum dot, the binding energy exhibits di?erent trends with the increase of core size at di?erent impurity locations. But the binding energy decreases monotonically with the shell size for both of them. Moreover, when the photon energy is approximately equal to the donor binding energy, the peak of the photoionization cross-section appears. There will be di?erent peak shifts under di?erent conditions, and its peak intensity increases with the increase of core and shell sizes. When the hydrostatic pressure is applied, the binding energy and the peak strength of the photoionization cross-section increase with the increase of the pressure.
关键词： hydrostatic pressure,Spherical quantum dot,binding energy,photoionization cross-section
更新于2025-09-19 17:13:59
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Enhancing the performance of heterogeneously coupled InAs Stranski-Krastanov on submonolayer quantum dot heterostructures
摘要： A detail investigation on enhancing the performance of heterogeneously coupled Stranski–Krastanov (SK) on Submonolayer (SML) quantum dot (QD) heterostructure has been done in this study. Different approaches have been implemented on the heterostructures to extend the emission wavelength towards telecommunication window. Strain reducing capping layers such as InxGa1-xAs, InxAlyGa1-x-yAs and GaAs1-xSbx has been considered for optimizing the discussed SK on SML QD heterostructures. Impact of different configurations on the hydrostatic and biaxial strain profile as well as carrier localization has been examined. Furthermore, by implementing these configurations, the photoluminescence wavelength was extended from the previously reported wavelength (1.1 μm) towards the telecommunication window (1.3 μm), which would impact the growth and fabrication of different optoelectronic devices in the near future.
关键词： Strain,Hydrostatic,Capping layer,Photoluminescence,Quantum dots,Biaxial
更新于2025-09-11 14:15:04